Stranded rope comprising endless, synthetic plastic threads



STRANDED ROPE COMPRISING ENDLESS, SYNTHETIC PLASTIC THREADS Filed June 18, 1965 INVENTORS HANS RICHARD SCHMITTMANN KARL HAPTMA NN A TTORNEYS United States Patent 3,274,765 STRANDED ROPE COMPRISING ENDLESS, SYNTHETIC PLASTIC THREADS Karl Hartmann, Cologne-Stamrnheim, and Hans-Richard Schmittmann, Leverkusen, Germany, assignors to Farbenfabriken Bayer Aktiengesellschaft, Leverkusen, Germany, a corporation of Germany Filed June 18, 1965, Ser. No. 465,055 7 Claims. (Cl. 57-144) The invention relates to a stranded rope or cable comprising endless, synthetic plastic threads, in which the strands are provided with fibre tows consisting of parallel plastic elementary filaments inserted externally between the surface threads; the tows may optionally be of twisted or braided structure.

In known ropes of this type, the fibre tows have a supporting function and thereby increase the breaking load of the rope. Under high loading and load relaxation, and on account of reversible stretching of threads and fibre tows, the ropes do however have a tendency to slide and slip on, for example, warping drums. As a result, frictional heat is evolved and the temperature can very quickly rise to a value at which the plastic surface threads of the stranded rope soften, and the breaking load of the rope is considerably reduced.

It has now been found that this disadvantage is avoided if the fibre tows are inserted in the strands as non-supporting rope elements without initial tension and have a count ratio of 30 to 45% relative to the adjacent surface, and either have a twisted formation with a degree of twisting which results from a twisting constant of /Nm to ZVM advantageously l.35 /Nm to 1.65 /Nm, wherein Nm represents the metric number of the fibre tow, or a braided formation with a braiding angle of 30 to 45.

The result of this is that, during use of a rope, for example when running over warping drums, the elementary filaments of the fibre tows inserted as non-supporting rope elements split off (the degree of twisting or the braiding angle determining the necessary rapid splitting) and thus form a brush-like irregular of flulfy fleece, which is uniformly distributed over the entire rope surface, the count ratio being effective in establishing a fleece which completely encloses the surface threads and prevents the premature wear which is particularly caused by the heat of friction, because it considerably improves the resistance to slipping and sliding of the rope. If the count ratio is too small, a fleece is indeed gradually formed as the rope is used, but this fleece does not enclose the surface threads and consequently does not offer any adequate protection against frictional heat. The same also applies as regards the known splitting effects which occur during normal wear and which lead to a slight fleece formation which does not sufliciently enclose the surface of the rope.

It is only with a count ratio of 30 to 45% relative to the adjacent threads, and with the use of a twisting of /Nm to ZVJW or a braiding angle of 30 to 45", that those parts of the fibre tows inserted on the outside of the strands and exposed on the surface of the stranded rope become so worn when the rope is being used for the first time on, for example, warping drums, because of their higher elongation at break as compared with the surface threads, i.e. the supporting rope elements, that the stranded rope immediately acquires a dense irregular Patented Sept. 27, 1966 or fluffy fleece of split fibres on its surface. Apart from the protection of the supporting rope elements and the better resistance to slipping of the ropes on winches and similar apparatus, the good handle of the rope surface is considerably improved, and the danger of accidents is reduced.

The fluify fleece leads to the rope having a considerably longer effective life.

One embodiment of the invention is shown diagrammatically and by way of example in the accompanying drawings in which FIGURE 1 is a cross-section through a stranded rope consisting of polyamide, before use, and FIGURE 2 is a cross-section through the same rope after use when the rope comprises a brush-like fibre fleece.

On account of the lateral pressure of the strands and the reversible rope elongation, those inserted fibre tows which are at the points of contact between two adjacent strands also become fiuffy.

The polyamide stranded rope comprises, for example, 8 strands, each strand comprising a surface layer of 8 plastic threads 1-8, each for example, with a diameter of 4 mm. Inserted without initial tension on the outside of each strand in the gaps between the surface threads 1 to 8, are 8 plastic fibre tows, 9 to 16. Each strand has a core 17 of elementary plastic filaments and the stranded rope has a core 18, which likewise consists of elementary plastic filaments. The plastic fibre tows 9 to 16 likewise consist of elementary plastic filaments which are arranged parallel to one another and which have, as desired, a twisted and/or braided structure. Since, for example, each plastic thread of the surface layer of a strand has a diameter of 4 mm., the running length of this thread is about m/kg., which means that 1000 metres of threads have a weight of 15,400 g. This corresponds to a count of 139,600 denier. In order to obtain an adequate fibre fleece when the stranded rope is first used, the count of the fibre tows 916 must be in the ratio of about 1:3 to that of the adjacent plastic threads 1-8; this means that the fibre tow must have a total count of about 45,000 denier. The fibre tows then have a running length of about 200 m./kg.; this corresponds to a metric number, Nm, of 0.2.

When the strand has a surface layer of 4 mm. threads and fibre tows of 45,000 denier, these fibre tows must have a certain degree of twisting in order to guarantee the rapid splitting of the elementary filaments on first use. This specific degree of twisting is calculated from a twisting constant of /Nm to 2 /N m advantageously 1.35 /Nm to 1.65 /Nm of the fibre tow, with the metric number 0.2 inserted for Nm. The result is 0.74 twist to to 1" length of the tow.

We claim:

1. A stranded rope of synthetic plastic material comprising strands formed of surface filaments stranded about a core and having fiber tows consisting of parallel elementary plastic filaments inserted externally between the surface filaments wherein said fiber tows in said strands are non-supporting rope elements having substantially no initial tension, said fiber tows being inserted between the surface filaments to prevent wear of said filaments.

2. A stranded rope as claimed in claim 1, wherein said fiber tows have a count ratio with respect to their adjacent surface filaments of about 30 to 45 percent.

3. A stranded rope as claimed in claim 2, wherein said fiber tows have a twisted structure.

3 4 4. A stranded rope as claimed in claim 3, wherein said 7. A stranded rope as claimed in claim 6, wherein said fiber tows have a degree of twisting of about W to fiber tows have a braiding angle of about 30 to 4 5. ZVAT, where Nm is the metric number of the fiber tow. Referemes Cit d by th Examiner 5. A stranded rope as claimed in claim 3, wherein s ag 5 UNITED STATES PATENTS fiber towsgve a degree 0t twlstrng 01: about 1.35 /Nm 3,111,001 11/1963 Schmittmann et a]. 57 144 to 1.65 /Nm, where Nm is the metric number of the 3,217,484 9 5 Ponemon 5 5 XR fiber tow.

6. A stranded rope as claimed in claim 2, wherein said MERVIN STEIN Primary Exammer' fiber tows have a braided structure. 10 D. E. WATKINS, Assistant Examiner. 

1. A STRANDED ROPE OF SYNTHETIC PLASTIC MATERIAL COMPRISING STRANDS FORMED OF SURFACE FILAMENTS STRANDED ABOUT A CORE AND HAVING FIBER TOWS CONSISTING OF PARALLEL ELEMENTARY PLASTIC FILAMENTS INSERTED EXTERNALLY BETWEEN THE SURFACE FILAMENTS WHEREIN SAID FIBER TOWS IN SAID STRANDS ARE NON-SUPPORTING ROPE ELEMENTS HAVING SUBSTANTIALLY NO 